Americans who watched the collapse of the World Trade Center towers on TV and reported feeling anxiety afterward also experienced increased rates of various heart ailments in the following three years.

That's the conclusion of a recent scholarly article in the Archives of General Psychiatry. Such research, showing intriguing connections between physical health and states of mind, has come in a steady flow for decades. While some studies are challenged or discredited, others replace them.

Ordinary Americans seem more comfortable than medical researchers with the idea that thoughts can control experience. The idea is embedded in popular culture: In the 1950 musical "Guys and Dolls" the humorous song "Adelaide's Lament" tells the story of a woman whose frustration in not getting married brings on a cold.

But what exactly is the relationship between mind and body? How strong is it? How is it evoked and how does it work?

In The Cure Within,Anne Harrington traces the mind-body connection through the centuries and in its many manifestations. Harrington, chair of the history of science department at Harvard University, finds that mind-body medicine is really a "patchwork" of widely differing beliefs and approaches that often "pull in different directions."

The many manifestations of mind-body healing make for fascinating reading, though her own conclusion on the subject is no more definitive than "let a thousand therapies bloom" alongside conventional, technological medicine.

The reductionist, "physicalist" medicine of today views disease as wholly a material phenomenon, she says. Disease has no meaning beyond being a natural physical process. Yet patients continue to seek out alternative meanings and methods. They see stories in their illnesses. Understanding these stories, they feel, will help lead to wholeness. When their bodies fail them, when they fall ill, people want to know the "why" questions: They ask "Why me? Why now? What next?" she says.

A broader tent for treating disease, Harrington says, would allow "that there is more to physical illness than can be seen just in the body; and more to healing than can be found in just pills and shots. Mind matters too: how one thinks, how one feels, what kind of personality or character one has or cultivates."

In the book readers encounter individuals such as 18th-century physician Franz Anton Mesmer and his form of healing through hypnotism, called mesmerism; Sigmund Freud and the birth of psychoanalysis, which explores the idea that "every illness was more than just a biological event; it was also a biographical event rich with (usually hidden) meaning...."

In the mid-20th century, Norman Vincent Peale, pastor of the Marble Collegiate Church in New York City, wrote a wildly popular book, "The Power of Positive Thinking,"urging ordinarily Americans to employ mind-body ideas to help themselves. Writer Norman Cousins's "The Anatomy of an Illness (as Perceived by the Patient)" told how he defeated his own severe physical ailment through laughter (including watching Marx Brothers movies). Harvard cardiologist Herbert Benson Westernized meditation as healing through his "relaxation response."

In her own research, Harrington has studied the "placebo effect" – the ability of fake drugs or even fake surgery to heal, an effect that continues to perplex researchers. In a broader sense, she asks, might peoples' bodies today listen and respond to scientists or doctors, "people they believe to speak with the authority of science"? We need to reflect on the "larger implications" of what that would mean, Harrington says.

Religion is a taproot for today's secular explorations into mind-body connections, she acknowledges. The Bible is filled with physical healings accomplished through prayer only. Some modern-day Christian denominations, such as Christian Science, emphasize physical healing. But Christian Science, for example, does not see true healing as the result of the action of the human mind, but as the natural effect of communing with the divine Mind, or God. To many religious adherents, religious healing is much more than the "supercharged placebo effect" Harrington grants it.

One way of looking at mental healing suggests that love may have a lot to do with it. In 2000, Robert Putnam, the author of "Bowling Alone," noted: "As a rough rule of thumb, if you belong to no groups but decide to join one, you cut your risk of dying over the next year in half." Statistically, feeling part of a group was about as effective in improving health as stopping smoking.

Studies of children separated from their parents in wartime Britain, postwar Germany, and later in state orphanages in communist Romania, showed that babies given adequate food, shelter, clothing, and medical care, but without attention from a mother or other loving caregiver, fell ill and died at a higher rate than those whose physical care was less good but who received loving attention. Even in a less-than-sanitary women's prison nursery in the United States, researchers found that "The mothers' love had proven a better deterrent to infection than the most conscientious of good hygiene practices," Harrington says.

Applying the power of the human mind to the body continues today to evoke healing effects, even if the causes behind them and their potential as reliable therapies remain a subject of debate. Might human mind-over-matter only hint at something more at work? Harrington doesn't go that far, but she does seem convinced that exploring – and even employing – the mind-body connection is a worthwhile endeavor.